Some addresses on Etherscan like this one show both type of transactions (ERC20 and ERC721) on Etherscan. So, does that mean that both standards can be implemented at the same time for a token?
ERC Standards – Can a Contract Address Handle Both ERC20 and ERC721 Transactions?
eiperc-20erc-721etherscango-ethereum
Best Answer
That looks like the contract is the recipient of both types of tokens. The contract might have functionality to also transfer the tokens out of it but it might not. If it doesn't have such functionality the tokens simply stay there and can never be transferred out of it.
You can't implement both of the standards in one contract as they have overlapping function names - the function signatures are somewhat similar (maybe even the same, didn't compare too closely) but the actual implementation can only be for one token type.